Adaptable Measuring Instrument for Wireless Dynamic Strain Monitoring on Moving Objects

Dynamic strain monitoring provides valuable information about behavior and condition of mechanical parts subjected to the load either under test or realistic working conditions. In many occasions, test points for strain measurement are not easily accessible for temporary or permanent wired connection with standard test and measurement equipment, especially for measurements on moving objects. We developed a configurable portable dynamic strain monitoring system, which is particularly suitable for short-term installations and adaptable for wide range of expected strain values. The high-accuracy measuring module, attached to the test point along with the strain gage sensor, digitizes and transmits measured data over the license-free ISM radio-frequency band to the receiving unit for further signal processing and results representation. The calibration procedure is highly simplified due to the specific design of the input analog measuring chain, which eliminates the need, in several commercially available similar instruments, for manual sensor calibration. The accuracy and the bandwidth of the input measuring chain were optimized to provide means for high quality spectral analysis of acquired dynamic strain waveforms. The system may be simply extended for dynamic torque, power and rotational speed measurements on revolving shafts, by connecting to the inductive proximity switch to the receiver module. Receiving unit also provides means for connection with other test and measurement equipment by standard analog and digital industrial communication protocols (4–20 mA current loop, RS485). The overall system was designed to accommodate to wide variety of test and research applications, as well as monitoring parameter ranges.Copyright © 2008 by ASME